81444417 has 16 divisors (see below), whose sum is σ = 110082048. Its totient is φ = 53557200.

The previous prime is 81444413. The next prime is 81444439. The reversal of 81444417 is 71444418.

It is not a de Polignac number, because 81444417 - 2² = 81444413 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81444413) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 73288 + ... + 74390.

It is an arithmetic number, because the mean of its divisors is an integer number (6880128).

Almost surely, 2^81444417 is an apocalyptic number.

It is an amenable number.

81444417 is a deficient number, since it is larger than the sum of its proper divisors (28637631).

81444417 is a wasteful number, since it uses less digits than its factorization.

81444417 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1420.

The product of its digits is 14336, while the sum is 33.

The square root of 81444417 is about 9024.6560599283. The cubic root of 81444417 is about 433.4647372037.

Subtracting from 81444417 its reverse (71444418), we obtain a palindrome (9999999).

It can be divided in two parts, 8144 and 4417, that added together give a triangular number (12561 = T₁₅₈).

The spelling of 81444417 in words is "eighty-one million, four hundred forty-four thousand, four hundred seventeen".